In June, Bitcoin Magazine reported that Blockstream launched Sidechain Elements, a sidechain development framework with open source code, including an experimental sidechain for developers dubbed Elements Alpha. Now, in the first technical post to appear on the Blockstream blog after the announcement of Sidechain Elements, Blockstream and Bitcoin Core developer Pieter Wuille proposes the intriguing concept of Tree Signatures, an efficient multisig method with enhanced privacy.
Blockstream was formed by renowned cryptography experts, including some Bitcoin Core developers, to accelerate innovation in digital currencies and implement the sidechain concept described in the paper “Enabling Blockchain Innovations with Pegged Sidechains,” released in October. In November, Blockstream closed a $21 million seed funding round with nearly 40 high-profile investors.
Tree signatures, which can be coded only in the extended Alpha scripting language, can implement M-of-N multisig transactions (which required more than one keyholder to participate) more efficiently than Bitcoin scripting. Wuille shows how to combine Merkle trees and Schnorr signatures to implement large M-of-N multisig schemes:
“Merkle tree keys support very